A federal appeals court ruled Tuesday against a major part of the Affordable Care Act, also known as Obamacare.

A three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit determined that tax credits and subsidies can’t be used to purchase health insurance through the federal exchange, healthcare.gov.

The 2-1 court decision found that an IRS rule interpreting the tax credits to apply to all exchanges was inaccurate under the law’s language — and that the wording of the law only applied to states. It reversed the lower court’s decision.

“This broader interpretation has major ramifications,” the court opinion said. “By making credits more widely available, the IRS Rule gives the individual and employer mandates — key provisions of the ACA — broader effect than they would have if credits were limited to state-established exchanges.”

The opinion said that applying the tax credits to all ACA marketplaces would require more people to have insurance under the individual mandate (because of the percentage income insurance would cost) and more businesses with more than 50 employees to offer health insurance or pay fines, expanding the mandates.

Court judges wrote that although all parties argued that the ACA showed clear intent, “they dispute what that intent actually is” — whether it applied only to states or if the federal government is “standing in the state’s shoes” when it creates an exchange.

“Although our decision has major consequences, our role is quite limited,” the opinion said.

Later Tuesday, a second decision took the opposite side, with the Fourth Circuit federal appeals court in Richmond, Va., ruling in favor of government subsidies, The New York Times reported, the latest move involving the controversial, embattled law. It affirmed the IRS’s right to offer the tax credits on all exchanges and Congress’ intent.

“Denying tax credits to individuals shopping on federal Exchanges would throw a debilitating wrench into the Act’s internal economic machinery,” the court’s opinion said. All three judges agreed.

“It is therefore clear that widely available tax credits are essential to fulfilling the Act’s primary goals and that Congress was aware of their importance when drafting the bill,” it said.

Subsidies are central to the ACA, with thousands enrolling in new health insurance plans believing they would help to offset the costs of the now-mandatory coverage.

About 4.5 million people who qualified for federal exchange subsidies could lose financial help to pay for their health insurance because of the D.C. court ruling.

The New York Times report shows that the plaintiffs argued that Congress had limited subsidies to state exchanges to encourage them to create their own. States were encouraged, but not required, to set up their own exchanges.

Just 14 states and Washington, D.C., set up their own online insurance exchanges under the ACA, with the remaining 36 offering health insurance through the federal marketplace.

California was the first state to set up its own, creating Covered California in 2010. Estimates show that roughly 60,000 valley residents are eligible for insurance through the exchange.